Electric light bulb unit



y 1957 J. a. DICKSON 2,799,794

ELECTRIC LIGHT BULB UNIT Filed July 22, 1953 INVENTOR. $2 77 5 ilk/1 5077,

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ntncrnrc molar BULB UNIT John B. Dickson, Highland Park, Mich, assignor to Chrysler (Iorporation, Highiand Park, Mich a corporation of Delaware Application duly 22., 1953, Serial No. 369,683

2 Claims. (Cl. 313318) This invention relates to improvements in an electric light bulb unit.

More particularly, the invention is directed to an electric light bulb unit, including a filament containing bulb part and a base part, which can be assembled relative to a support by inserting the bulb part through an opening in a support and threading the base part into engagement with the wall of the opening.

An object of the invention is to provide, in a unit of the foregoing type, a base part including a section having a uniform diameter and a threaded surface designed to accommodate limited threading of the base section into a support opening and to effect wedging engagement with the wall of such opening to thereby limit travel of the base section into the opening.

A further object of the invention is to provide in a unit of the foregoing type a base part having a threaded surface, the pitch of the threads thereof varying to eifect wedging engagement of the base in the support opening.

Other objects and advantages of the invention will be more apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is an enlarged elevational view, partly in section, showing an electric light bulb unit embodying the invention and mounted relative to a support.

Fig. 2 is a longitudinal sectional view, in elevation, of the Fig. 1 showing.

The electric bulb unit includes a bulb part 5 and a metallic base part 6 secured together by a body of basing cement 7 of insulating material. The bulb part 5 has a relatively small end extending into the base part 6, and while the latter part is shown as filled with the basing cement 7, it will be understood that the body of cement used can be confied to the telescoping portions of parts 5 and 6 in securing the latter together. The end of base 6 opposite the bulb receiving end has a closure 8, an edge portion 9 of which is held in a channel section at 10 of the base. A hollow rivet 11 extends through an opening in the base and has its inner and outer ends respectively flanged over the inner and outer faces of the closure 8, the outer flange securing a conducting prong 12 to the closure, which prong 12 is adapted to be connected with a source of electrical energy.

The bulb 5 is provided with a filament 14 supported by a pair of conventional conductors 15 one of which is connected with the rivet 11 and the other with the metallic base 6.

The base 6 is shown as a metallic sleeve, a section 13 of which has a threaded external surface and a uniform diameter. The unit is adapted to be secured to a sup port 16 having an opening 17 and the maximum diameter of the bulb part is sufficiently less than the diameter of the opening 17 and base section 13 to accommodate insertion of the bulb part through the opening and threading of the base section therein. The support is extended at the opening to provide an axial sleeve 18 although the wall bounding the opening may be merely Ice the thickness of the support in case the latter is relatively large and maybe sufliciently threaded to permit the desired threaded engagement of the support and base.

It is desirable to firmly attach the unit to the support, preferably by wedging engagement of the threaded base section in the opening, such opening limiting travel of the base into the opening. This wedging engagement is accomplished by varying the pitch of the threads on the external surface of the base section 13. As illustrated, the axial extent of the threaded surface 13 is much greater than the threaded surface of the support and only a relatively small portion of the surface 13 will be engaged with the wall of the opening 17 when the unit is assembled to the support.

Successive thread convolutions beginning at the bulb end of the base have a pitch which will permit threading of the base into the support opening to an extent sufiicient to support the bulb unit. The pitch of such convolutions varies sufliciently to efiect a wedging engagement of the unit with the support assuming, of course, that the threads of the support wall are of uniform pitch which is the preferred embodiment.

For a firm mounting of the unit, the first thread convolution of the section 13 can be threaded through the support opening and the pitch of subsequent thread convolutions varies so that the latter thread convolutions have wedging engagement. The change in thread pitch involves an increase in the axial dimension of the threads at successive convolutions. As a result the thread groove of the wall 18 will not wholly contain a thread convolution of the base section 13, that is to say such thread convolution will not bottom at the base of the thread groove of the wall 16 but will bear against and wedge with side faces of such groove. This is illustrated by the somewhat exaggerated spacing at 17 in Fig. 1.

The lines A, B, C in Fig. 1 illustrate the variation in thread pitch at the second, third and fourth thread convolutions, counting from the bulb end of the base, and it will be noted that this change is a gradual one. While the axial extent of the inter-threading and wedging engagement as shown is sufficient for mounting the unit on the support, nevertheless the additional threading and pitch variation can be utilized to compensate for variation in hole diameter.

The support wall 16 may constitute a space enclosing wall or may be so related to other structure that the opening is accessible only from right to left as viewed in Fig. 1 and the illumination is desired at the left hand side of such wall. In either event the bulb part 5 is inserted in a direction from right to left through the opening for threading of the base section 13 therein.

I claim:

1. An'electric light bulb unit including a base part and a filament containing bulb part secured thereto, the base part including a portion having a uniform diameter and a threaded surface adapted for threaded engagement with a support, the diameter of said base part being larger than the diameter of said bulb part, certain of the threads of said surface having a pitch differing from the pitch of other threads of said surface and the threads of said surface having a common groove depth.

2. An electric light bulb unit adapted to be secured to a support having an opening bounded by a threaded wall, the unit comprising a base part including a tubular section having a uniform diameter and a threaded external surface for threaded engagement with the wall bounding the support opening, a filament containing bulb part secured to the base part and projecting from one end of said tubular section, said bulb part having a dimension smaller than a like dimension of said support opening to accommodate insertion of the bulb part through said opening, the threads of said tubular section having a common depth, certain of the threads of said tubular sec- 'tion adjacent said one end thereof having a pitch dimensupport opening and limit travel of said tubular section into said support opening.

References Cited in the file of this patent UNITED STATES PATENTS Cross et al Oct. 11, 1927 Fagerlund Aug. 7, 1934 Criger et al. Oct. 25, 1938 Dickson July 14, 1953 wok n 

